Rules: Standard Sudoku rules (insert a number in the indicated range into each cell so that no number repeats in any row, column, or bold region). Some digits are given outside the grid. These digits must appear in the first three cells in the corresponding direction.

Answer String: Enter the row/column marked “A”, followed by a comma, followed by the row/column marked “B”. Rows are entered from left to right and columns from top to bottom. This example has the key “736241859,687415392”.

(Brief) History of Outside Sudoku: Descended from Sudoku puzzles and other variations. Outside Sudoku was created by Leo Colovini, an Italian board game designer, and first published by Studiogiochi. It was featured at the first World Sudoku Championship in Lucca, Italy where it gained broader exposure.

History of this example: This Outside Sudoku was written by Thomas Snyder for Sudoku Cup 3.

Sources for Outside Sudoku: Follow this link for Outside Sudoku puzzles on this website. If you are new to this puzzle type, here are our easiest Outside Sudoku to get started on. More Outside Sudoku puzzles can be found in Masterpiece Sudoku Mix 4 and in the (out of print) Mutant Sudoku.

Design rules for contributors: A Grandmaster Outside Sudoku will have a unique solution that can be reached by logic alone. Generally, a Grandmaster Outside Sudoku has a symmetric layout of numbers or an interesting theme in the numbers or both. No given numbers should appear inside the grid at the beginning.